Toxic mucus traps: A novel mechanism that mediates prey uptake in the mixotrophic dinoflagellate Alexandrium pseudogonyaulax
Toxic mucus traps: A novel mechanism that mediates prey uptake in the mixotrophic dinoflagellate Alexandrium pseudogonyaulax
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DOI：
10.1016/j.hal.2012.02.010
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发表时间：
2012-05-01
期刊：
影响因子：
6.6
通讯作者：
Hansen, Per Juel
中科院分区：
文献类型：
--
作者：
Blossom, Hannah E.;Daugbjerg, Niels;Hansen, Per Juel
在许多情况下，海洋浮游藻类产生的有害物质（即毒素）的功能作用仍然未知。这项研究描述了一种新的机制，通过这种机制，光养甲藻Alexandiumpseudogonyaulax分泌一种有毒的粘液陷阱，捕获猎物并在摄食前固定。猎物细胞仍然被困在粘液陷阱中，不动，但大多数保持完整，随时可以作为全细胞猎物。结果表明，A. pseudogonyaulax即使在营养充足、光照充足的条件下也能显著提高其生长速度。生长速率的提高在限光处理中更为明显，而在A.在两种光照条件下，以圆形异囊藻为饵料的假沟藻生长速度均显著快于以尖叶苔为饵料的假沟藻。为了比较，研究了链状亚历山大藻和微小亚历山大藻的菌株的兼养能力。在所提供的条件下，这些菌株都不是兼养型的。此外，还比较了这些亚历山大藻菌株以及塔玛亚历山大藻和奥氏亚历山大藻对各种原生生物靶标的毒性作用。假角蕨属A. tamarense和A.与所有的A. pseudogonyaulax研究。结果表明，A.假gonyaulax是非特异性的，在相对低的细胞浓度（500细胞/ml供体细胞）下几乎100%固定各种原生生物素靶。不需要临界供体细胞密度，因为只有一个A。pseudogonyaulax细胞能够引起靶细胞的固定。这是第一次，排泄的毒素和摄食之间的联系是明显的Alexandrum物种和这种特殊的策略有可能严重影响竞争的浮游植物群落。(C)2012爱思唯尔有限公司版权所有。
The functional role of harmful substances (i.e. toxins) produced by marine planktonic algae is still, in many cases, unknown. This study describes a novel mechanism by which the phototrophic dinoflagellate Alexandrium pseudogonyaulax secretes a toxic mucus trap where prey items are caught and immobilized prior to ingestion. Prey cells remain entrapped and immobile in the mucus trap, but most stay intact, readily available as whole-cell prey. It is shown that food uptake by A. pseudogonyaulax increases its growth rate considerably even in nutrient-replete, high-light conditions. The increase in growth rate was more enhanced in light-limited treatments and A. pseudogonyaulax grew significantly faster when fed Heterocapsa rotunda to, than when fed Teleaulax acuta under both light conditions. For comparison, strains of Alexandrium catenella and Alexandrium minutum were studied for their mixotrophic capabilities. None of these strains were mixotrophic under the conditions provided. In addition, the toxic effects on various protistan targets of these Alexandrium strains as well as Alexandrium tamarense and Alexandrium ostenfeldii were compared to that of A. pseudogonyaulax. A. tamarense and A. catenella did immobilize and lyse target cells through substances leaked directly into the water, differing from all the strains of A. pseudogonyaulax studied. Results show that the toxic effect of A. pseudogonyaulax is nonspecific causing nearly 100% immobilization of a variety of protistan targets at relatively low cell concentrations (500 cells ml(-1) of donor cell). A critical donor cell density was not required as only one A. pseudogonyaulax cell was able to cause immobilization of target cells. For the first time, the connection between excreted toxins and phagotrophy is evident in an Alexandrium species and this particular strategy has the potential to severely impact competing phytoplankton communities. (C) 2012 Elsevier B.V. All rights reserved.